1. Field of the Invention
This invention relates to feedthrough of optical fibers and in particular but not exclusively to feedthrough into device packages.
2. Description of the Prior Art
Device packages that incorporate an optical or opto-electronic component have an aperture for the feedthrough of the optical fibers that conduct light to or from the package. It has been usual practice to support the connecting portion of the fibers in a metal sleeve and then for the sleeve to be mounted in the aperture, the fibers being held in the sleeve by a metal solder or epoxy resin.
If a fiber is to be soldered into the sleeve it is necessary to metallize the fiber so that the metal solder will adhere to the fiber and the additional handling of the delicate fiber during the metallization process can cause damage, especially to the end of the fiber which in some instances will already have been provided with a lens. The lensing process cannot be performed easily after metallization because the proximity of a metal surface tends to interfere with the arc discharge technique generally employed. Also, metal solder is subject to creep and this can lead to loss of alignment of the fiber to the optical or opto-electronic device, and over the course of time it may even creep sufficiently to cause loss of hermetic sealing between the fiber and sleeve.
On the other hand if epoxy resin is used to hold the optical fibers in position there is a slow release of gases from the resin (even after heat treatment) and the gases that are discharged can be harmful to components within the package. A further problem that is encountered with both metal solder and epoxy resin is that the fiber may not be concentric with the sleeve and therefore the precise position of the fiber may not be known so that once the sleeve has been aligned it is necessary to perform compensating adjustments in order to ensure alignment of the optical fiber with the opto-electronic or optical component in the package.
The present invention is directed towards providing a hermetic seal between an optical fiber and a feedthrough sleeve utilizing glass solder.